Piston sealing device



fnvrvior 7 4 W 0 m m 1 m m J J 3 0w 0 fl W g Dec. 12, 1944. E. ERICSSONPISTON SEALING DEVICE Filed Oct. 19, 1942 Patented Dec. 12, 1944 UNITEDSTATES PATENT OFFICE PISTON SEALING DEVICE Elov Ericsson, St. Paul,Minn. i I Application October 19, 1942, Serial No. 462,501 (ensue-2s) i6 Claims.

This invention relates to a device for sealing pistons for pneumaticsprings, shock absorbers and the like, and particularly to sealingdevices of the general character described in my application Serial No.287,563, filed July 31, 1939.

It is an object of this invention to' provide novel means for preventingthe loss of oil or other liquid or lubricant contained in the cylinderwhile affording efiicient lubrication and returning lubricant from thewalls of the cylinder to a piston recess or reservoir.

The invention will be best understood by reference to the accompanyingdrawing in which:

Figure 1 is a central vertical section through a cylinder and pistonprovided with myimproved sealing device;

Fig. .2 is a fragmentary section on a larger scale showing details ofthe invention;

Fig. 3 is a plan view of the arcuate leaf sprin members, and

Fig. 4 is a side view of said members together with the overlyingcontact ring or bearing member.

As illustrated, my device is mounted on a piston indicated generally bythe numeral 5 which is slidable in a cylinder 6 having a chamber 1 intowhich air or other gas under pressure may be charged through. a valve 8.The piston 5 is hollow having a chamber 9 and a head indicated generallyby thenumeral ID. The chambers 1 other end fastened to the lower end ofthe piston.

Formed in the head I0 is a chamber; 11 for oil which isheld underpressure by the airor'other gas in the chamber '1. 1 Immediately belowthe chamber I1 is a compressible sealing member 18 preferably of thecharacter described and claimed in my application Serial No. 287,563.This member is expanded against the cylinder wall by the pressureexerted in the high pressure chamber H, but allows some oil to be forceddown along the cylinder Walls thus affording eflicient lubrica tion andimproving the seal; By the present invention I guard against loss of theoil form ing this lubricating film.

Mounted in the piston Wall below thesealing member I8 is a secondsealing member,indicated generally by the numeral I9, formed from rubberor rubber-like compressible material and having a skirt portionextending along the cylinder wall and flanges 20 and 2| projecting infrom its upper and lower extremities respectively.

' The inner peripheries. of these flanges are tightly and 9 are incommunication with each other 7 through a passage ll extending axiallythrough a tube l2 which is fixed on the upperend of the cylinder 6 andextends axially through a central bore in the piston head I0. Nearitsupper end the tube 12 communicates with chamber 1 through a passageIla which is restricted by an adjustable plug Ilb. At its lower end thetube I2 isfitted with a disk l3 fitting the Walls of the chamber 9 tocushion the rebound of the piston in use. The air or other gas in thechamber 9 passes from one side of the disk l3 to the other inlongitudinal grooves I4 formed in the interior of the piston walls butthese grooves terminate a short distance below the up er extremity ofthe chamber 9 to prevent contact between the disk and end of thechamber. To connect the lower end of the piston to the mechanism to becontrolled, a stud I5 is provided and the body of the cylinder 6 may besecured to the frame or relatively movable mechanism. Enclosing theprojecting portion of the piston to protect it against accumulations ofdirt or other foreign matter is a flexible cover l6 having one endconnected to the lower end of the cylinder and the gripped between metalparts of the. piston head, as hereinafter described. The upper fiange 20is oiiset downward to aflord an annular'recess 22'.

which is in communication with the outer periphery. of the piston andcylinder wall by means of a plurality of radially extending perforations23. These perforations are spaced slightly above the upper end of thesealing member I9 to allow lubricant to pass to and from the recess 22which functions as a reservoir for the lubricant.

Immediately below the flange 20 and recess 22 is a small annular airchamber containing a series of arcuate spring members 24 and anoverlying contact ring 25. Each of the spring members 24 comprises athin band of spring metal which is preferably'of sinuous form andadapted to re siliently support the overlying ring 25 and flexibleflange 20, thusallowing the recess 22 to expand or increase its capacityto receive oil under pressure which would otherwise be forced past themember 19, as hereinafter more fully de scribed.

' To control and distribute the pressure exerted by the member 19against the wall. of the cylinder, I provide an arrangement of splitrings like that described and claimed in 'my application Serial No.287,563. These include a ring 26 forming the outer Wall of the chamber'22'and rings 21 and 28 operating against the inner or low pressureface. of the, member l9 to distribute the radial pressure thereon fromwithin. The piston head l0 and sealing members l8 and 19 are connectedto the upper end of the piston 5 by a series of concentric threadedmembers 29, 30 and 3|, the latter having a threaded connection with thelower end portion of the head In and the member 29 having a similarconnection with the tubular piston body.

In operation, under the varying thrust exerted on the piston, the latteris given reciprocating motion within the cylinder and the fluid pressurein the latter normally returns the piston to a predeterminedposition inwhich 'itmay remain. for a considerable period of time. During such,periods of rest and even when the piston is in motion some oil is forcedfrom the chamber [1: past the upper sealing member l8 and down along thecylindrical walls until it reache the'sealing member I9. Some oil entersthe annular-recess 22 through the radial perforations 23 to fill thenear its high pressure face, a second sealing same and transmit pressurewhich is directed 3 radially outward upon the expansible ring 26. Thispressure is transmitted to the member I9 by the rings-21 and28.- Theresulting expansion of member lllfurther limits the escape of'liquidtowardthe low pressure end of the cy e During the subsequent upwardmovement of the piston in the cylinder the oil is wipedfrom the cylinderwall with considerable force by the" sealing member l9 and cannot escaperapidly. up:- Ward because-of the sealing member l8. Such" additionaloil is forced through the radial perforations 23 into the chamber 22whichis allowed to expand and receive it due to the compression oftheleaf springs 24 under the increased: pressure. The oil which is'thusforced into the. expanding chamber 22 is retained above the seal:- ingmember I9 instead of being-forced downpast that member. Upon the returnor down: stroke of the piston pressure along the cylinder wall above thesealing member l9 is'partially. relieved. with the result that the leafsprings 24uexpandand force out some oil from the chamber 22? againstthecylinder wall surfacesbetween the sealing members l8.and l9. Itwillthusbei'evident that my device prevents the pumping out of the oil alongthe cylinder walls by producing; a reverse pumping action and affordinga more? elfective seal.

The amount of oil which passes to and. from. the annular recess 22through'the radial-perforations 23 issmall and consequently only slightcompression and expansionof the leaf springs 24 in" the annular air.chamber beneath the flange.

20 is required. Ordinarily, pressures-:on the order.

of several hundred pounds per square inch. are carriedin the chamber 1and the leaf springs: 24 must be designed to permit slight deflection;under the corresponding pressuresin the annular:- recess 22 while thecontact ring 25 afiordsa continuous support for the flexible flange2n'above the springs. I

Having described my invention, what I- claim. as new and desire toprotectbyLetters. Patent is:

1.,In combination with a. piston, an annular expansible sealing memberembracing the piston" near its high pressure face, a second sealing;member embracing the piston in spaced relation to said firstmentionedsealing.member, a recess for liquid formed in the piston,aseparate cham' her, a flexible member separating said chamberfrom'said" recess'and a metallic spring confined in said chamber'andsubject to pressure in' said-l recess for permitting expansion of saidrecess to receive additional liquid, said recess' being in com--munication with the outer periphery of the piston: between. said sealingmembers;

member embracing the piston in spaced relation to said first mentionedsealing member, a recess for liquid and a separate chamber, formed inthe piston, a flexible member separating said chamber from said recessand resilient, compressible means confined in said chamber and subjectto pressure in said recessior permitting expansion of said recess" toreceive additional liquid, said recess being in communication with theouter periphery of the piston between said seal-.

said members,- said skirt being expansible: out'-.

ward and: subject to radial pressure in. said re cess; achamber/separated from. said. recess-by a flexible .portion of.saidsecond sealing member and resilient, compressible means in-saidchamber subject to pressure in saidrecess'for'permitting" expansion ofsaid recess'to receive additionalliq uid, saidrecessbeing incommunication withxthe 1 outer periphery. of thepistonbetweensaidsealing.

members.

4. In.- combination with a. piston, an' annular expansible sealing.member having a. skirt: em.- bracingthe piston and a flexible,annulartflange projecting inward from-z saids'kirt, an: annular:

recess for liquid formed in the piston adjacent.

to'said flange, an annularv chamber: separated from said recess by. saidflange and. resilient'com'i pressible means confined. in said; chamber;and

subject to pressure in said recess for permitting:

expansion-0f saidrecess to receive additionalliquid; said recess.beingin-communication with the; outer periphery of the piston.

5. In combinationwith a piston, an: annular expansible sealingmemberfhaving a. skirt'embracing the piston. and having aflexiblexannulan flange projecting inward from. said skirt,flan.an--

nularrecessforliquid formed-in theppiston-gadjas cent'to said flange, anannularchamber-sepa.- rated from said recess byxsaid' flange and: an:arcuate leaf spring confined in-said chamber; and". subject topressure'in' said recessfor permitting;

expansion ofsaid recess-to. receive additionalliqe uid, saidrecess-being in communication .withithet:

outer periphery ofrthe piston.

said" flange and between saidzsealing members,v

an annular 'chamberseparatedv from :said .rece'ss1= by saidj flangexand:resilient, compressible means:

confined. insaid. chamber and subject to. press sure inisaid-recess forpermittingexpansion of? v said recess .to receiveadditional liquid, saidrecess: being'in communicationwith the outer periph-= ery: of: the"piston between said: sealing members ELOV: nnrossoN!

